Monoclonal antibodies will be formed by fusing spleen cells from immunized mice with the mouse myeloma cell line P3-X63-Ag8. The mice will have been immunized with human epidermal cells, human epidermal cell membranes and human keratins. The epidermal cells used as antigens will be from normal epidermis, epidermal tumors including basal cell carcinoma, squamous cell carcinoma and keratoacanthoma; epidermis from patients with psoriasis, various forms of ichthyosis, Darier's disease, Hailey-Hailey disease, and other genetic disorders of keratinization. Fused cell will be grown in selective media; cells producing antibodies to antigens limited to epithelial or epidermal tissues will be cloned and studied further. The nature of the antigen will be defined using immunofluorescent, electron microscopic, and immunoprecipitin procedures. The antigen will be isolated by immunoprecipitation and its molecular weight and isoelectric electric point determined, and attempts to identify the antigen with known tissue constituents will be made. Monoclonal antibodies will be tested on a wide variety of cultured cells, and human tissues to determine the tissue specificity of the antigen; antigenic changes in neoplastic and non-neoplastic diseases of epithelia will be determined; cells will be fractionated biochemically to determine the cellular location of the antigen. Changes in antigenicity as a function of aging will be studied. Using monoclonal antibodies which have a specificity restricted to human keratin, and not mouse keratins, gene mapping of the keratin genes in human epidermal cells will be begun. Those studies will involve fusion of cultured human and mouse epidermal cells. Drug resistance and temperature will be used to select against the parental cell types and only hybrid cells will grow. Hybrids will be tested for human keratin by polarizing microscopy, histological staining, immunofluorescence, 2-dimensional SDS-electrophoresis and isoelectric focusing, and immunoassay of the cellular contents. Cells containing human keratin will be karyotyped, cloned and subcloned so that chromosomal localization can be obtained.